On Dec 16, 2008, at 9:07 AM, Poul-Henning Kamp wrote:
http://www.navcen.uscg.gov/cgsic/meetings/48thmeeting/Reports/Timing%20Subcommittee/48-LS%2020080916.pdf
Thanks for posting this - extremely helpful!
On Dec 16, 2008, at 10:47 AM, Poul-Henning Kamp wrote:
Please discontinue use of your "d
Rob Seaman scripsit:
> For instance, I happen to think your notion about perpetually
> revolving the time zone offsets around the planet under completely
> local authority is spectacularly unworkable.
Why are such changes in timezone unworkable, provided they
don't happen too often? The me
Because the past remains with us, and the future requires planning.
By discarding any stationary mapping from local clocks (and calendar)
to an underlying "universal" timescale, historical provenance and long
range planning acquire a spatially dependent error term that grows
with time. Th
On Wed 2008-12-17T19:23:16 -0700, Rob Seaman hath writ:
> The historical trend
> (http://www.ucolick.org/~sla/leapsecs/ancient.png ) won't just vanish with
> the actions of the ITU, it will pop up again somewhere else.
I appreciate the link to the LOD plot, and I have faith in the
readership of
In message <20081218030954.ga26...@ucolick.org>, Steve Allen writes:
>http://www.ucolick.org/~sla/leapsecs/deltat.html
I belive your LORAN-C TOC is wrong, that should be 01-01-1958 00:00:00 UTC
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 9
Rob Seaman scripsit:
> Because the past remains with us, and the future requires planning.
What the past tells us is that prediction is very difficult, *especially*
about the future. At sea, where no one cares much, the timezone mappings
have remained stable; on land, it's a different story,
In message: <10573.1229588...@critter.freebsd.dk>
"Poul-Henning Kamp" writes:
: In message <20081218030954.ga26...@ucolick.org>, Steve Allen writes:
:
: >http://www.ucolick.org/~sla/leapsecs/deltat.html
:
: I belive your LORAN-C TOC is wrong, that should be 01-01-1958 00:00:00 UTC
I
On Thu 2008-12-18T10:28:38 -0700, M. Warner Losh hath writ:
> Although the epic of LORAN-C TOC is indeed 1958, LORAN-C TOC followed
> the 'rubber seconds' from 1958 until 1972 when leap seconds were
> introduced. After that, its course is parallel to UTC without further
> leap seconds.
And if I h
John Cowan wrote at 11:15 -0500 on Dec 18, 2008:
> Rob Seaman scripsit:
> > Because the past remains with us, and the future requires planning.
In addition to what John Cowan said, I'd also point out that planning
is the one of the biggest issues with leap seconds.
In terms of planning for t
On Dec 18, 2008, at 9:15 AM, John Cowan wrote:
The median number of changes over the century-give-or-take of standard
time (exactly when standard time begins depends on the jurisdiction)
is 3, minimum 1, maximum 17 (!), mean 3.94, standard deviation 2.88.
Even if we ignore all changes before the
Rob Seaman scripsit:
> And how precisely is this making your point? In the absence of a
> coherent zoneinfo scheme like Steve Allen's, you are asserting that
> the (literally) rock solid basis of mean solar time anchored deep in
> the Earth,
Nothing anyone can do will change the value of m
So, the assertion is that an imaginary requirement that technology
worldwide must remain synchronized to the fractional second level at
all times in all places forever and ever - that this takes precedence
over the actual (if heretofore largely unstated) requirement that
historians and long
I should make the aside that these debates seem to pop up "like
clockwork" every year around this time :-)
Regardless of everyone's entrenched positions, a most Happy New Year!
On Dec 18, 2008, at 2:46 PM, John Cowan wrote:
I'm pointing out that we are *already* doing that when establishing
In message <5a9295bc-1704-489c-b4b1-2942c0414...@noao.edu>, Rob Seaman writes:
>We live on a planet with charmingly irregular motions. Attempting to
>ignore this fact will inevitably fail, perhaps spectacularly.
Before the first timezone ever shifts to compensate for the abandoned
leapseconds,
Rob Seaman wrote:
I should make the aside that these debates seem to pop up "like
clockwork" every year around this time :-)
Probably because leapseconds tend to be around this time. :)
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Rob Seaman wrote at 14:50 -0700 on Dec 18, 2008:
> So, the assertion is that an imaginary requirement that technology
> worldwide must remain synchronized to the fractional second level at
> all times in all places forever and ever - that this takes precedence
> over the actual (if hereto
On Dec 18, 2008, at 3:13 PM, Poul-Henning Kamp wrote:
Before the first timezone ever shifts to compensate for the abandoned
leapseconds, that number is almost certain to have increased to at
least two and likely more irregular rocks.
Scroll back the the very beginning of the archives. I had s
Poul-Henning Kamp wrote:
>A timescale which takes earth rotation into account should be
>called "Terrestial Time Coordinated" (TTC ?) and the timescale
>that takes into account the rotation of Mars should be MTC.
The name "MTC" has already been used to refer, not to the Martian
equivalent of UTC,
In message: <18762.53127.165662.23...@gromit.timing.com>
John Hein writes:
: > Solutions for "applications" can and should rely on properly designed
: > systems
:
: Indeed. And relying on a system whereby you receive six months notice
: is one of the problems with the current sys
Rob Seaman wrote:
>historians and long term planners (and yes, some folks do think
>thousands of years into the past and the future) need a coherent
>system for tracking clock relationships between countries and centuries?
Historians have to relate whatever time scale was historically in use
t
Rob Seaman scripsit:
> >Why should mumans on Mars or the Moon, care about the rotation of
> >a rock they are not on when they want to time events ?
>
> Well, because they likely want to communicate with their families back
> on Earth, I suppose, but again you are making my point. What are you
On Dec 18, 2008, at 4:27 PM, Zefram wrote:
I think the more fundamental issue is that we will, any way round,
need data that relates the two flavours of time. A single clock
reading can't give both types of time in the absence of such
knowledge.
...and wouldn't a description of how these
On Dec 18, 2008, at 9:45 PM, John Cowan wrote:
Ah, but will Lunar civil time be mean solar time on Luna?
For many purposes, yes. The Apollo missions were planned to occur in
daylight, for instance. For other purposes, the factor of ~30
contrast between the lunar day and the innate human
At 2008-12-18 23:50 -0700, Rob Seaman wrote:
GPS is a very popular brand name that could certainly be used as a
component of a successful campaign to market a new concept of civil
timekeeping.
Please, no. I've had to spend a lot of time explaining the difference
between GPS time as used in the
Rob Seaman scripsit:
> One supposes the lunar synodic period would be divided into 30 parts.
*One* may suppose it, but others have not, such as Manuel Garcia
O'Kelly-Davis, an actual (though fictional) resident of Luna, describing
the timescale discussions of the "Ad-Hoc Congress for Organization
On Dec 19, 2008, at 10:34 AM, John Cowan wrote:
Rob Seaman scripsit:
One supposes the lunar synodic period would be divided into 30 parts.
*One* may suppose it, but others have not, such as Manuel Garcia
O'Kelly-Davis, an actual (though fictional) resident of Luna,
describing
the timescal
On Fri, 19 Dec 2008, Rob Seaman wrote:
>
> To synchronize two clocks (Earth and Lunar in this case), you can adjust
> the rates on one end or the other, or you can reset the zero point of
> one or the other on some sort of schedule. Additionally, if the
> differential rates continue to vary, then
Tony Finch wrote:
> The local atomic clocks on the Moon or Mars will not run at the
>same rate as a time signal transmitted from the Earth.
More due to being at high altitude than due to relative motion, I believe.
If you're concerned about local interval time, with a sufficiently heavy
em
Tony Finch wrote:
On Fri, 19 Dec 2008, Rob Seaman wrote:
To synchronize two clocks (Earth and Lunar in this case), you can
adjust
the rates on one end or the other, or you can reset the zero point of
one or the other on some sort of schedule. Additionally, if the
differential rates continu
I wrote:
>Tony Finch wrote:
>> The local atomic clocks on the Moon or Mars will not run at the
>>same rate as a time signal transmitted from the Earth.
>
>More due to being at high altitude than due to relative motion, I believe.
I've just found this relevant graph on Wikipedia:
http://up
On Mon, 22 Dec 2008, Zefram wrote:
>
> http://upload.wikimedia.org/wikipedia/commons/9/98/Orbit_times.png
Cool, thanks for that and the interesting details in your other post.
Tony.
--
f.anthony.n.finchhttp://dotat.at/
WIGHT PORTLAND PLYMOUTH: VARIABLE BACKING SOUTHEAST 3 OR 4, OCCASIONALLY
In message <037ba1cd-da84-4ae9-8623-657f4cf8e...@noao.edu>, Rob Seaman writes:
>3) My own point of view focuses on the requirements for "wall
>clocks". Civil timekeeping has (heretofore) been mean solar time
>[...]
You mean "has been within a couple of hours of mean solar time" ?
>4) The IT
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